Security Analysis Of Some Symmetric Algorithms

With the continuous changes and improvements in information technology, informationsecurity becomes more and more important in the Internet age. As the theoretical core of theinformation security, the cryptography provides basic protection for the secure transmission ofdata. What’s more, the modern cryptography could be divided into two types: symmetriccryptography and asymmetric cryptography, and the symmetric cryptography is one of the coreresearch areas of cryptography. The symmetric cryptography includes block ciphers, hashfunctions and stream ciphers, and has many attractive features such as fast speed, small storageand simple implementation. As a major branch of symmetric cryptography, block cipher has beenwidely used in many fields, such as file transfer, network communication, database systemsecurity and so on. As another active branch of symmetric cryptography, Hash function is widelyused in digital signatures, files integrity and authentication schemes, etc.With the rapid development of intelligent hardware and embedded technology, andlarge-scale application of cryptographic devices, a new class of attack, called side channel attack,on cryptographic devices has been public. According to the software and hardware faultinformation that leaked from the cryptographic devices, secret key or plaintext could be retrievedrapidly based on this attack. As one type of effective side channel attack, differential fault attack isa popular cryptanalysis by inducing faults on cryptographic equipment and combining withdifferential technique. Due to these characteristics of strong attacking ability, fast speed, andsimple implementation, it has attracted wide attention from scholars and researchers in domesticand overseas.This dissertation proposes an effective method of fault attacks on Serpent algorithm, GOSTalgorithm and MD5compression function, and conducts software simulation and verification.Furthermore, a fault detection method of MD4algorithm is described in this dissertation. Themain innovative research achievements of this dissertation are summarized as follows:First of all, on the basis of the byte-oriented model and the differential analysis, an effective differential fault attack on the Serpent cryptosystem is proposed. Mathematical analysis andsimulating experimental results show that the attack could recover its128bits secret key byintroducing48faulty ciphertexts. In addition, it provides a common method for the analysis of thesame type of other iterated cryptosystems.Secondly, on the basis of the byte-oriented fault model and the differential analysis, adifferential fault attack on the GOST cipher by inducing faults is proposed. The simulatingexperimental results show that the attack could recover its256-bit secret key by introducing32faulty ciphertexts. The attacking method on the GOST cipher not only extends the attacking scopeof faults, but also increases the efficiency of fault injection and decreases the number of faultyciphertexts.Thirdly, depending on word-oriented fault model and the differential analysis, a newdifferential fault attack on the MD5compression function is presented. The simulatingexperimental results show that only144faults are required to recover the current input messageblock for the MD5compression function. It provides a new reference for the security analysis ofthe hash functions with structure similar to the MD5.Lastly, in terms of the principle of differential fault attack, a detection method of the MD4algorithm against differential fault attack is presented. According to the detection method, it couldbe judged whether the current MD4algorithm is attacked by differential fault attack or not.Simultaneously, the fault location and effectiveness of the fault injection could be determined. Thedetection method has a significant reference value for the research on other cryptographicalgorithms against differential fault attack.